Diffusion and thermal conductivity of the mixture of paraffin and polystyrene for thermal energy storage: A molecular dynamics study. Issue 4 (August 2017)

• Record Type: Journal Article
• Authors: Liu, Xinjian; Lin, Changpeng; Rao, Zhonghao
• Is Part Of: Journal of the Energy Institute. Volume 90:Issue 4(2017:Oct.)
• Page Start: 534
• Page End: 543
• Publication Date: 2017-08
• Subjects: Paraffin -- Polystyrene -- Molecular dynamics -- Diffusion -- Thermal conductivity; Power (Mechanics) -- Periodicals; Power resources -- Periodicals; Fuel -- Periodicals; 621.04205
• DOI: 10.1016/j.joei.2016.05.008
• Languages: English
• ISSNs: 1743-9671

Abstract

Abstract: The development of thermal energy storage material is of vital importance to relieve the severe challenges of energy crisis. Phase change material and microencapsulated phase change material for energy storage is an important branch of thermal energy storage technology. In this paper, the simplified amorphous cell model was constructed with n-octacosanoic (C28 H58 ), n-docosane (C22 H46 ) and polystyrene (PS), which was used to investigate the heat and mass transfer of this system by performing molecular dynamics (MD) and non-equilibrium molecular dynamics methods (NEMD). The simulation results showed that the self-diffusion of this system will enhance with increasing temperature. Furthermore, higher temperature contributes to the extension of catenulate molecules, especially for polystyrene, which actually enhances the mass transfer of system. In addition, the thermal conductivity of the system increases with continuously increasing temperature, but the values are lower than that of pure paraffin. Therefore, the high thermal conductivity additives are required to be added into the mixture in order to improve the ability of heat transfer of the material. Highlights: The microscopic details of the MEPCM composed of paraffin and PS was investigated by MD and NEMD methods for the first time. The diffusion and structural properties of the system were analyzed by calculating MSD, RDF and radius of gyration. The thermal conductivity was obtained by non-equilibrium molecular dynamics simulations to study heat transfer of the system. The polystyrene weakened the diffusion and the thermal response of the system. The MEPCM composed of paraffin and PS possessed lower thermal conductivity compared with the pure paraffin.